摘要:

PAOLONE, A. M., M. SHANGOLD, D. PAUL, J. MINNITTI, and S. WEINER. Fetal heart rate measurement during maternal exercise—avoidance of artifact.Med. Sci. Sports Exerc., Vol. 19, No. 6, pp. 605–609, 1987. The purpose of this study was to investigate the possibility that motion artifact may override the recording of fetal heart rate (FHR) with Doppler ultrasound fetal monitors during maternal exercise on cycle ergometers and treadmills, and to test the efficacy of two-dimensional ultrasound directed M-mode echocardiographs for determining FHR during maternal treadmill exercise. Four pregnant women (26 to 30 yr, X = 28, gestational age = 28 to 34 wk) pedaled a cycle ergometer at 25 to 50 W, while a second group (N= 4) (24 to 36 yr, X = 29, gestational age = 30 to 37 wk) walked on a treadmill at either 1.5 or 2.0 mph. Fetal monitor recordings (Hewlett-Packard 8040A) were consistent with pedal rate in the range of 50 to 70 rpm and with stepping rate in the range of 70 to 76 steps per min at 1.5 mph and 100 to 106 steps per min at 2.0 mph on the treadmill. Actual mean FHRs (audible signal from fetal monitor) were in the normal range [150.5 ± 10.25 bpm (cycle ergometer) and 148.8 ± 2.3 bpm (treadmill)]. In a separate session, the cycle ergometer group walked on a treadmill at a maternal heart rate of 140 bpm while FHR was determined by two-dimensional ultrasound directed M-mode echocardiographs. Off-line analysis of fetal cardiac cycle time (clinical graphics analyzer) allowed accurate FHR measurements which were not confounded by motion artifact. Mean FHR during maternal treadmill exercise (158.0 ± 12.0 bpm) was not different (P > 0.05) when compared to pre-exercise standing (140 ± 3.6) and also during the post-exercise period (sitting) (151 ± 6.5) compared to the sitting pre-exercise measurements (147 ± 8.2). It was concluded that M-mode echocardiographs of fetal cardiac activity during maternal exercise provide artifact-free determinations of FHR and that the apparent fetal bradycardia during maternal exercise reported by other investigators is most likely motion artifact.

ISSN:0195-9131    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

PÉRONNET, F., G. THIBAULT, E. C. RHODES, and D. C. MCKENZIE. Correlation between ventilatory threshold and endurance capability in marathon runners.Med. Sci. Sports Exerc., Vol. 19, No. 6, pp. 610–615, 1987. The purpose of the study was to develop an index of endurance capability [i.e., “the ability to sustain a high fractional utilization of maximal oxygen uptake (VO2max) for a prolonged period of time”]. The index was based on the linear reduction of fractional utilization of VO2maxwith total running time greater than 7 min plotted on a log scale. The endurance index estimated from VO2maxrunning efficiency and the marathon performance of 18 male runners (30 ± 7 yr old; VO2max= 66 ± 5 ml.kg-1.min-1) ranged between −4.07 and −9.96% VO2ma*.ln t-1(mean ± SD = −6.40 ± 1.50) and was not related to VO2max(r = 0.107) or speed in the marathon race (r = 0.354). However, the endurance index was closely related (r = 0.853) to the fractional utilization of VO2maxat ventilatory threshold (breakaway of the excess CO2elimination curve) which occurred at 76.1 ± 5.5% VO2maxin response to a graded treadmill test. These results indicate that: (i) running time on long distance races is not, per se, an adequate measure of endurance capability because of the major contribution of VO2maxto long distance running performance; (ii) the endurance index expressed as %VO2max.1n t-1is an objective and independent index of endurance capability; and (iii) runners with a high endurance capability tend to hyperventilate at higher relative workload during a graded treadmill test.

ISSN:0195-9131    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

GRABINER, M. D. and V. JAQUE. Activation patterns of the triceps brachii muscle during sub-maximal elbow extension.Med. Sci. Sports Exerc., Vol. 19, No. 6, pp. 616–620, 1987. This study was conducted to assess the effects of practice/learning upon the electromechanical delays (EMD) of each head of the triceps brachii, the “true” EMD, “activation lag” periods, and the activation order associated with this multi-pennate muscle. Eight subjects participated in the study. Bipolar surface electrodes detected electromyographic signals (digitized at 1,000 Hz) from each of the three heads of the triceps brachii muscle. The task used was elbow extension with the forearm attached to, and supported by, a dynamometer. Each subject performed 10O trials (analyzed in groups of 10 trials) at approximately 70% the previously established maximum peak acceleration. Analysis consisted of calculating the EMD of each head of the triceps, “true” EMD (time from the first head's activation to movement) activation lag time (difference between the first and last activated heads EMD), and activation order. Correlations between EMD and peak acceleration for the three heads were found to be low, consistent with previous research, and the relationship was not improved by use of the true EMD. Activation lag times were found to decrease (non-significantly) over the 100 trials. Activation order was found to vary widely between subjects but as a group favored the medial head. Results of this study appear to support the contention that the “product” nature of EMD measure is of less merit than generally considered and that a more “process”-related parameter would provide better information regarding peripheral processes.

ISSN:0195-9131    

出版商:OVID    

年代:1987

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1987

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1987

数据来源: OVID